Resist composition and patterning process

ABSTRACT

The present invention is a resist composition comprises a polymer compound having one or two repeating units selected from repeating units represented by the following general formulae (p-1), (p-2) and (p-3), a repeating unit represented by the following formula (a-1) and the formula (a-2) polarities of which are changed by an action of an acid, and a repeating unit represented by the following formula (b-1); a salt represented by the following general formula (B); and a solvent, wherein a difference of a C log P of the repeating unit (a-1) before and after changing the polarity is 3.0 to 4.5, and a difference of a C log P of the repeating unit (a-2) before and after changing the polarity is 2.5 to 3.2. This provides a resist composition which has high sensitivity, wide DOF and high resolution, reduces LER, LWR and CDU, and has good pattern shape after exposure and excellent etching resistance.

TECHNICAL FIELD

The present invention relates to a resist composition and a patterningprocess using the resist composition.

BACKGROUND ART

Accompanied with high integration and high speed of LSI, miniaturizationof pattern rule is progressing rapidly. In particular, expansion offlash memory market and increase in memory capacity are leading tominiaturization. As the state-of-the-art miniaturization technology,mass production of a device with 65 nm node by ArF lithography is beingcarried out, and preparation of mass production of 45 nm node by ArFimmersion lithography of the next generation is now in progressing. As32 nm node of the next generation, there are candidates of immersionlithography by ultra-high NA lenses using a liquid having a higherrefractive index than that of water and a lens having a high refractiveindex, and a higher refractive index material in combination, extremeultraviolet (EUV) lithography with a wavelength of 13.5 nm, ArFlithography with double exposure (double patterning lithography), andthe like, and investigation is in progressing.

In order to improve resolution and dimensional controllability in highenergy beam, the resist film tends to be low sensitivity. Lowering insensitivity of the resist film leads to lowering in productivity, whichis not preferable. From the demand of making high sensitivity,chemically amplified type resist materials are being investigated.

With the progress of miniaturization, edge roughness (line edgeroughness: LER and line width roughness: LWR) of line patterns anddimension uniformity (critical dimension uniformity: CDU) of holepatterns are regarded as problems. It has been pointed out thatdissolution contrast of a base polymer to a developing solution,influence of localization or agglomeration of an acid generator, andinfluence of acid diffusion. Further, accompanied with thinning of theresist film, LER tends to be large, and deterioration of LER and etchingresistance by thinning the film accompanied with the progress ofminiaturization is a serious problem.

In the formation of a positive type fine line pattern, when a basepolymer containing a bulky and high-contrast acid leaving group is used,it becomes a T-top shape, and deterioration of edge roughness andclogging of hole pattern occur. To the contrary, when a base polymercontaining a compact acid leaving group is used, a residual filmthickness of an unexposed portion to the developing solution is loweredand the pattern is easily collapsed. It has been desired to develop anexcellent resist by taking a balance between the dissolution contrastand control of acid diffusion to improve resolution.

In Patent Document 1, it has been reported that lithographiccharacteristics are remarkably improved by using two kinds of photoacidgenerators having different acid strengths. In Patent Document 2, it hasbeen reported that density dependence of line and space becomes small byusing a sulfonium salt which generates an alkane sulfonic acid in whichthe a-position of the sulfonic acid is substituted by a fluorine atomand a sulfonium salt which generates an alkane sulfonic acid in whichthe a-position of the sulfonic acid is not substituted by fluorine incombination. In Patent Document 3, it has been reported that depth offocus of the hole pattern or the trench pattern and circularity or LWRare improved by using a polymer compound containing a photoacidgenerator which generates an alkane sulfonic acid in which thea-position of which has been substituted by a fluorine atom, with anacid generator generating an alkane sulfonic acid in which an a-positionof the sulfonic acid is not substituted by fluorine in combination. Thiseffect is attributed by the fact that acid strength of the alkanesulfonic acid in which the a-position of which has been substituted by afluorine atom is higher than that of the alkane sulfonic acid which isnot substituted by fluorine. These prior art techniques are consideredthat a strong acid generated from a photoacid generator by exposureperforms salt exchange with a weak acid onium salt to form a strong acidonium salt, whereby the strong acid having high acidity is replaced witha weak acid which suppresses an acid-generating decomposition reactionof an acid labile group to shorten an acid diffusion distance. That is,the weak acid onium salt is considered to function as a quencher (aciddeactivator) to the strong acid generated by exposure. As compared witha nitrogen-containing compound such as amines, etc., the weak acid oniumsalt is generally non-volatile, so that it can prevent from changing theconcentration of the surface layer of the resist film during formationof the resist film and a baking process for patterning, which makes itpossible to form good rectangular shape of the pattern.

In Patent Document 4, it has been reported that in the case of using anonium alkane sulfonate, the acidity thereof is not sufficiently low ascompared to a carboxylic acid onium salt, so that quenching ability islow, and resolution, edge roughness, depth of focus, etc. cannot besatisfied.

CITATION LIST Patent Literature Patent Document 1: Japanese PatentLaid-Open Publication No. 2000-241965 Patent Document 2: Japanese PatentLaid-Open Publication No. 2003-005376 Patent Document 3: Japanese PatentLaid-Open Publication No. 2012-137518 Patent Document 4: Japanese PatentLaid-Open Publication No. 2015-054833 SUMMARY OF INVENTION TechnicalProblem

The present invention has been made in view of the above-mentionedcircumstances, and an object thereof is to provide a resist compositionhaving high sensitivity superior to the conventional resist materials,wide depth of focus (DOF) and high resolution, being reduced in edgeroughness (LER and LWR) and critical dimension uniformity (CDU) of holepattern, having good pattern shape after exposure and excellent etchingresistance, which is a resist composition using a polymer compoundsuitable as a base resin of the resist composition and a salt excellentin control of acid diffusion, and a patterning process using the resistcomposition.

Solution to Problem

In order to achieve the above-mentioned tasks, in the present invention,it is provided a resist composition including: a polymer compound havingone or two repeating units selected from repeating units represented bythe following general formulae (p−1), (p-2) and (p-3), a repeating unitrepresented by the following formula (a-1) and the formula (a-2)polarities of which are changed by an action of an acid, and a repeatingunit represented by the following formula (b-1); a salt represented bythe following general formula (B); and a solvent,

wherein a difference between a C log P of the repeating unit (a-1) and aC log P of the repeating unit (a-1) after changing the polarity thereofby an action of an acid is 3.0 to 4.5, and a difference between a C logP of the repeating unit (a-2) and a C log P of the repeating unit (a-2)after changing the polarity thereof by an action of an acid is 2.5 to3.2.

(In the above-mentioned formulae (p-1), (p-2) and (p-3), R¹, R⁴ and R⁶are each independently a hydrogen atom or a methyl group. Z¹ is a singlebond, a phenylene group, —O—Z(═O)—O—Z¹¹— or —C(═O)—NH—Z¹¹—, Z¹¹ is analkanediyl group having 1 to 6 carbon atoms or an alkenediyl grouphaving 2 to 6 carbon atoms, or a phenylene group, each of which maycontain a carbonyl group, an ester bond, an ether bond or a hydroxylgroup. Z² is a single bond, —Z²¹-C(═O)—O—, —Z²¹—O— or —Z²¹—O—C(═O)—, Z²¹is an alkanediyl group having 1 to 12 carbon atoms, and may contain acarbonyl group, an ester bond or an ether bond. R² to R³ are eachindependently a monovalent hydrocarbon group having 1 to 20 carbon atomswhich may contain a hetero atom(s). R⁵ is a hydrogen atom or atrifluoromethyl group. Z³ is a single bond, a methylene group, anethylene group, a phenylene group, a fluorinated phenylene group,—O—Z³¹—, —C(═O)—O—Z³¹— or —C(═O)—NH—Z³¹—, Z³¹ is an alkylene grouphaving 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylenegroup, a phenylene group substituted with a trifluoromethyl group, or alinear, branched or cyclic alkenylene group having 2 to 6 carbon atoms,each of which may contain a carbonyl group, an ester bond, an ether bondor a hydroxyl group. Also, M¹⁺ represents a counter cation having asubstituent(s), and represents a sulfonium cation, an iodonium cation oran ammonium cation. M⁰⁻is a non-nucleophilic counter ion. In theabove-mentioned formula (a-1), R⁷ is a hydrogen atom or a methyl group.Y has a structure that changes its polarity by an action of an acid andbecomes soluble in an aqueous alkali solution. In the above-mentionedformula (a-2), R⁸ is a hydrogen atom or a methyl group. Z⁴ is a singlebond, a methylene group, an ethylene group, a phenylene group, afluorinated phenylene group, —O—Z⁴¹—, —C(═O)—O—Z⁴¹— or —C(═O)—NH—Z⁴¹—,Z⁴¹ is an alkanediyl group having 1 to 12 carbon atoms, and may containa carbonyl group, an ester bond or an ether bond. R⁹ to R¹¹ eachindependently represent a hydrocarbon group which is linear having 1 to10 carbon atoms, or branched or cyclic having 3 to 10 carbon atoms, andtwo of which may be bonded to each other to form a ring. In theabove-mentioned formula (b-1), R¹² is a hydrogen atom or a methyl group.Z⁵ is a single bond, a methylene group, an ethylene group, a phenylenegroup, a fluorinated phenylene group, —O—Z⁵¹—, —C(═O)—O—Z⁵¹— or—C(═O)—NH—Z⁵¹—, and Z⁵¹ is an alkanediyl group having 1 to 12 carbonatoms, and may contain a carbonyl group, an ester bond or an ether bond.n1 is an integer of 1 to 3, n2 is an integer of 0 to 3 and a sum of n1and n2 is 5 or less. R¹³ is a halogen atom or a hydrocarbon group whichis linear having 1 to 10 carbon atoms, or branched or cyclic having 3 to10 carbon atoms, —CH₂— constituting the hydrocarbon group may bereplaced by —O—, —C(═O)—O— or —C(═O)—, or a hydrogen atom constitutingthe hydrocarbon group may be substituted with a halogen atom or a heteroatom;)

Ma-CO₂ ⁻M²⁺   (B)

(In the formula (B), Ma represents a linear, branched or cyclicmonovalent hydrocarbon group having 1 to 35 carbon atoms which maycontain an oxygen atom(s). Also, one or more hydrogen atoms bonded tothe carbon atom may be substituted with a fluorine atom(s); and M²⁺represents a counter cation having a substituent(s), and is a sulfoniumcation, an iodonium cation or an ammonium cation.)

When the resist composition of the present invention is employed, it hashigh sensitivity, wide depth of focus (DOF) and high resolution, reducesedge roughness (LER and LWR) and critical dimension uniformity (CDU) ofa hole pattern, and has a good pattern shape after exposure andexcellent etching resistance.

The resist composition of the present invention may have a structure inwhich the polymer compound further contains a repeating unit having alactone structure represented by the following general formula (c-1).

(In the formula (c-1), R¹⁴ is a hydrogen atom or a methyl group. X¹ is asingle bond or a hydrocarbon group having 1 to 5 carbon atoms and —CH₂—constituting the hydrocarbon group may be replaced by —O—, —C(═O)—O— or—C(═O)—. L is a group having a lactone structure.)

When such a resist composition is employed, the resist film to be formedbecomes a material having excellent adhesiveness, and a resist patternhaving a more preferable shape can be obtained.

In this case, L in the above-mentioned formula (c-1) is preferably agroup represented by any of the following formulae (c-1-1), (c-1-2) and(c-1-3).

(In the formula (c-1-1), n3 is an integer of 1 to 4, R¹⁵ is ahydrocarbon group which is linear having 1 to 10 carbon atoms, orbranched or cyclic having 3 to 10 carbon atoms, and —CH₂— constitutingthe hydrocarbon group may be replaced by —O—, —C(═O)—O— or —C(═O)—, or ahydrogen atom constituting the hydrocarbon group may be substituted witha halogen atom or a hetero atom. n4 represents a linking group having 1to 5 carbon atoms. In the formula (c-1-2), X² is a single bond or ahydrocarbon group having 1 to 5 carbon atoms and —CH₂— constituting thehydrocarbon group may be replaced by —O— or —C(═O)—. n5 is an integer of1 to 4, R¹⁶ is a hydrocarbon group which is linear having 1 to 10 carbonatoms, or branched or cyclic having 3 to 10 carbon atoms, and —CH₂—constituting the hydrocarbon group may be replaced by —O—, —C(═O)—O— or—C(═O)—, or a hydrogen atom constituting the hydrocarbon group may besubstituted with a halogen atom or a hetero atom. In the formula(c-1-3), X³ is a single bond or a hydrocarbon group having 1 to 5 carbonatoms and —CH₂-constituting the hydrocarbon group may be replaced by —O—or —C(═O)—. n6 is an integer of 1 to 4, R¹⁷ is a hydrocarbon group whichis linear having 1 to 10 carbon atoms, or branched or cyclic having 3 to10 carbon atoms, —CH₂— constituting the hydrocarbon group may bereplaced by —O—, —C(═O)—O— or —C(═O)—, or a hydrogen atom constitutingthe hydrocarbon group may be substituted with a halogen atom or a heteroatom.)

When such a resist composition is employed, the resist film becomes amaterial having more excellent adhesiveness.

In the resist composition of the present invention, the differencebetween a C log P of the repeating unit (a-1) and a C log P after thepolarity of the repeating unit (a-1) has been changed by an action of anacid is preferably 3.3 to 4.2.

When such a resist composition is employed, it is more difficultly tocause that the hole pattern is clogged or T-top shape is generated inthe line pattern, and the depth of focus becomes more preferable.

In addition, in the resist composition of the present invention, thesalt represented by the general formula (B) can be a salt represented bythe following formula (B1).

(In the formula (B1), R¹⁸ to R¹⁹ each independently represent a hydrogenatom, a fluorine atom or a trifluoromethyl group. R²⁰ represents ahydrogen atom, a hydroxyl group, a linear, branched or cyclic,substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, ora substituted or unsubstituted aryl group having 6 to 30 carbon atoms.M²⁺ represents a counter cation having a substituent(s), a sulfoniumcation, an iodonium cation or an ammonium cation.)

When such a resist composition is employed, a resist film excellent inresolution can be provided.

Also, the resist composition of the present invention may furthercontain a salt represented by the following formula (B2).

(In the formula (B2), R²¹ represents a hydrogen atom or atrifluoromethyl group. R²² represents a linear, branched or cyclicmonovalent hydrocarbon group having 1 to 35 carbon atoms which maycontain an oxygen atom(s). Also, one or more hydrogen atoms bonded tothe carbon atom may be substituted with a fluorine atom(s). M²⁺represents a counter cation having a substituent(s), a sulfonium cation,an iodonium cation or an ammonium cation.)

When such a resist composition is employed, acid strength of the oniumsalt can be controlled, so that a resist film more excellent inresolution can be provided.

Further, in the resist composition of the present invention, therepeating unit represented by the above-mentioned formula (a-2) can be arepeating unit represented by the following formula (a-2-1).

(In the formula (a-2-1), R⁸ to R¹¹ are as defined above.)

When such a resist composition is employed, swelling to the alkalinedeveloping solution can be more suppressed, collapse of pattern can beprevented, and depth of focus can be broadened.

In addition, the present invention is to provide a patterning processwhich is a patterning process which includes: forming a resist film on asubstrate using the above-mentioned resist composition, laying a maskover the resist film, exposing by irradiating a high energy beam, then,developing with an alkali developing solution to form a pattern on thesubstrate, wherein the exposure by the high energy beam is carried outby a KrF excimer laser having a wavelength of 248 nm, an ArF excimerlaser having a wavelength of 193 nm, EUV having a wavelength of 13.5 nm,or an electron beam.

When such a patterning process is employed, a resist pattern having highsensitivity, wide depth of focus (DOF) and high resolution, beingreduced in edge roughness (LER and LWR) or critical dimension uniformity(CDU) of a hole pattern, and having good pattern shape after exposureand excellent etching resistance can be formed.

Advantageous Effects of Invention

The resist composition of the present invention has a high alkalidissolution contrast before and after exposure, and has wide depth offocus and high resolution by preventing pattern collapse by suppressingswelling in an alkali developing solution and shows good pattern shapeand edge roughness after the exposure. Accordingly, a positive typeresist composition suitable for a pattern forming material particularlyfor manufacturing super LSI or for EUV exposure, and particularly achemically amplified positive type resist composition can be obtained.

DESCRIPTION OF EMBODIMENTS

As mentioned above, it has been desired to develop a resist compositioncapable of forming a resist pattern which has high sensitivity, widedepth of focus (DOF) and high resolution, is capable of reducing edgeroughness (LER and LWR) or critical dimension uniformity (CDU) of a holepattern, and has good pattern shape after exposure and excellent etchingresistance.

As a result of earnest studies to accomplish the above-mentionedobjects, it has been found that a resist composition containing apolymer compound having a repeating unit in which (meth)acrylic acid isprotected by an acid labile group, a repeating unit in which a phenolichydroxyl group is protected by an acid labile group and a repeating unitobtained from an onium salt has high sensitivity and high resolution,reduces line edge roughness (LER) and line width roughness (LWR), andenables fine processing in which pattern shape is good, whereby thepresent invention has been achieved.

That is, the present invention is directed to a resist composition whichincludes a polymer compound having one or two repeating units selectedfrom repeating units represented by the following general formulae(p-1), (p-2) and (p-3), a repeating unit represented by the followingformula (a-1) and the formula (a-2) polarities of which are changed byan action of an acid, and a repeating unit represented by the followingformula (b-1); a salt represented by the following general formula (B);and a solvent, wherein a difference between a C log P of the repeatingunit (a-1) and a C log P of the repeating unit (a-1) after changing thepolarity thereof by an action of an acid is 3.0 to 4.5, and a differencebetween a C log P of the repeating unit (a-2) and a C log P of therepeating unit (a-2) after changing the polarity thereof by an action ofan acid is 2.5 to 3.2.

(In the above-mentioned formula (p-1), (p-2) and (p-3), R¹, R⁴ and R⁶are each independently a hydrogen atom or a methyl group. Z¹ is a singlebond, a phenylene group, —O—Z¹¹—, —C(═O)—O—Z¹¹—, or —C(═O)—NH—Z¹¹—, Z¹¹is an alkanediyl group having 1 to 6 carbon atoms or an alkenediyl grouphaving 2 to 6 carbon atoms, or a phenylene group, each of which maycontain a carbonyl group, an ester bond, an ether bond or a hydroxylgroup. Z² is a single bond, —Z²¹—C(═O)—O—, —Z²¹—O— or —Z²¹—O—C(═O)—, Z²¹is an alkanediyl group having 1 to 12 carbon atoms, and may contain acarbonyl group, an ester bond or an ether bond. R² to R³ are eachindependently a monovalent hydrocarbon group having 1 to 20 carbon atomswhich may contain a hetero atom(s). R⁵ is a hydrogen atom or atrifluoromethyl group. Z³ is a single bond, a methylene group, anethylene group, a phenylene group, a fluorinated phenylene group,—O—Z³¹—, —C(═O)—O—Z³¹— or —C(═O)—NH—Z³¹—, Z³¹ is an alkylene grouphaving 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylenegroup, a phenylene group substituted with a trifluoromethyl group, or alinear, branched or cyclic alkenylene group having 2 to 6 carbon atoms,each of which may contain a carbonyl group, an ester bond, an ether bondor a hydroxyl group. Also, M¹⁺ represents a counter cation having asubstituent(s), and represents a sulfonium cation, an iodonium cation oran ammonium cation. M⁰⁻is a non-nucleophilic counter ion. In theabove-mentioned formula (a-1), R⁷ is a hydrogen atom or a methyl group.Y has a structure that changes its polarity by an action of an acid andbecomes soluble in an aqueous alkali solution. In the above-mentionedformula (a-2), R⁸ is a hydrogen atom or a methyl group. Z⁴ is a singlebond, a methylene group, an ethylene group, a phenylene group, afluorinated phenylene group, —O—Z⁴¹—, —C(═O)—O—Z⁴¹— or —C(═O)—NH—Z⁴¹—,Z⁴¹ is an alkanediyl group having 1 to 12 carbon atoms, and may containa carbonyl group, an ester bond or an ether bond. R⁹ to R¹¹ eachindependently represent a hydrocarbon group which is linear having 1 to10 carbon atoms, or branched or cyclic having 3 to 10 carbon atoms, andtwo of which may be bonded to each other to form a ring. In theabove-mentioned formula (b-1), R¹² is a hydrogen atom or a methyl group.Z⁵ is a single bond, a methylene group, an ethylene group, a phenylenegroup, a fluorinated phenylene group, —O—Z⁵¹—, —C(═O)—O—Z⁵¹— or—C(═O)—NH—Z⁵¹—, Z⁵¹ is an alkanediyl group having 1 to 12 carbon atoms,and may contain a carbonyl group, an ester bond or an ether bond. n1 isan integer of 1 to 3, n2 is an integer of 0 to 3 and a sum of n1 and n2is 5 or less. R¹³ is a halogen atom or a hydrocarbon group which islinear having 1 to 10 carbon atoms, or branched or cyclic having 3 to 10carbon atoms, —CH₂-constituting the hydrocarbon group may be replaced by—O—, —C(═O)—O— or —C(═O)—, or a hydrogen atom constituting thehydrocarbon group may be substituted with a halogen atom or a heteroatom;)

Ma-CO₂ ⁻M²⁺   (B)

(In the formula (B), Ma represents a linear, branched or cyclicmonovalent hydrocarbon group having 1 to 35 carbon atoms which maycontain an oxygen atom(s). Also, one or more hydrogen atoms bonded tothe carbon atom may be substituted with a fluorine atom(s); and M²⁺represents a counter cation having a substituent(s), and is a sulfoniumcation, an iodonium cation or an ammonium cation.)

In the following, the present invention will be explained in detail, butthe present invention is not limited by these.

[Resist Composition]

The resist composition of the present invention is directed to a resistcomposition which comprises a polymer compound having one or tworepeating units selected from repeating units represented by thefollowing general formulae (p-1), (p-2) and (p-3), a repeating unitrepresented by the following formula (a-1) and the formula (a-2)polarities of which are changed by an action of an acid, and a repeatingunit represented by the following formula (b-1); a salt represented bythe following general formula (B); and a solvent, wherein a differencebetween a C log P of the repeating unit (a-1) and a C log P of therepeating unit (a-1) after changing the polarity thereof by an action ofan acid is 3.0 to 4.5, and a difference between a C log P of therepeating unit (a-2) and a C log P of the repeating unit (a-2) afterchanging the polarity thereof by an action of an acid is 2.5 to 3.2.

The above-mentioned polymer compound is sensitive to high energy beam,heat and so on to generate an acid.

In the present invention, the high energy beam includes ultravioletrays, far ultraviolet rays, electron beams, EUV (extreme ultravioletrays), X-rays, excimer lasers, gamma rays, and synchrotron radiation.

As mentioned below, characteristics corresponding to the above-mentionedrespective repeating units are provided to the resist film obtained fromthe composition.

Styrene having an acid labile group is excellent in etching resistancethan methacrylate in which an ester is substituted with an acid labilegroup which is somewhat compact, and after the acid labile group iseliminated by an acid, an amount of swelling by an alkali developingsolution is small and pattern collapse is small.

From the viewpoint of dissolution contrast by an alkali developingsolution, a methacrylate protected by an acid labile group whichgenerates a carboxylic acid is more advantageous than the repeating unitwhich generates a phenolic hydroxyl group. However, generation of thecarboxylic acid causes swelling in the developing solution, and patterncollapse occurs thereby. On the other hand, in the case of a repeatingunit having an acid labile group which generates a phenolic hydroxylgroup, there is a merit that the amount of swelling is small, but ascompared with the type generating a carboxylic acid, dissolutioncontrast is inferior. Thus, in order to obtain both characteristics ofimprovement in dissolution contrast and reduction in the amount ofswelling, repeating units in which a methacrylic acid and a phenolichydroxyl group are protected by an acid labile group are protected.

The phenol group has a sensitizing action to EB and EUV, and has aswelling-suppressing effect in an alkali developing solution. By havingthe phenol group in the polymer compound, generation efficiency ofsecondary electrons and sensitization effect at the time of exposure areheightened, and decomposition efficiency of the acid generator isheightened whereby sensitivity is improved.

By containing the photoacid generator in the polymer compound, ascompared with the conventional addition type photoacid generator, it hasa high effect of suppressing acid diffusion, has high resolution andexposure margin, is excellent in process adaptability, and has goodpattern shape after exposure.

As compared with an α-fluoroalkane sulfonic acid, by using a weak acidonium salt in combination as a quencher component, the weak acid oniumsalt is generally non-volatile so that, as compared with anitrogen-containing compound such as amines, it can prevent fromchanging its concentration in the surface layer of the resist film atthe time of forming the resist film or during the baking process forpatterning, which makes it possible to form a good rectangular shape.Further, by using a carboxylic acid onium salt which has lower aciditythan that of the alkane sulfonic acid having no fluorine atom at thea-position and has high quenching ability as the weak acid onium salt,it has high effect in suppressing diffusion of the acid, has highresolution and exposure margin, and is excellent in processadaptability.

The resist composition of the present invention becomes a resistcomposition, by having the above-mentioned constitution, which can forma resist pattern having high sensitivity, wide depth of focus (DOF) andhigh resolution, being reduced in edge roughness (LER and LWR) andcritical dimension uniformity (CDU) of hole pattern, and having goodpattern shape after exposure and excellent etching resistance.

In the following, constitutional components of the resist composition ofthe present invention will be explained.

[Repeating Units (p-1), (p-2) and (p-3)]

The polymer compound constituting the resist composition of the presentinvention has one or two repeating units selected from the repeatingunits represented by the following general formulae (p-1), (p-2) and(p-3).

In the above-mentioned formulae (p-1), (p-2) and (p-3), R¹, R⁴ and R⁶are each independently a hydrogen atom or a methyl group. Z¹ is a singlebond, a phenylene group, —O—Z¹¹—, —C(═O)—O—Z¹¹- or —C(═O)—NH—Z¹¹—, Z¹¹is an alkanediyl group having 1 to 6 carbon atoms or an alkenediyl grouphaving 2 to 6 carbon atoms, or a phenylene group, each of which maycontain a carbonyl group, an ester bond, an ether bond or a hydroxylgroup. Z² is a single bond, —Z²¹-C(═O)—O—, —Z²¹—O— or —Z²¹—O—C(═O)—, Z²¹is an alkanediyl group having 1 to 12 carbon atoms, and may contain acarbonyl group, an ester bond or an ether bond. R² to R³ are eachindependently a monovalent hydrocarbon group having 1 to 20 carbon atomswhich may contain a hetero atom(s). R⁵ is a hydrogen atom or atrifluoromethyl group. Z³ is a single bond, a methylene group, anethylene group, a phenylene group, a fluorinated phenylene group,—O—Z³¹—, —C(═O)—O—Z³¹— or —C(═O)—NH—Z³¹—, Z³¹ is an alkylene grouphaving 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylenegroup, a phenylene group substituted with a trifluoromethyl group, or alinear, branched or cyclic alkenylene group having 2 to 6 carbon atoms,each of which may contain a carbonyl group, an ester bond, an ether bondor a hydroxyl group. Also, M¹⁺ represents a counter cation having asubstituent(s), and represents a sulfonium cation, an iodonium cation oran ammonium cation. M⁰⁻is a non-nucleophilic counter ion.

As the monomer which provides the repeating units (p-1), (p-2) and(p-3), for example, those described at the paragraphs [0068] to [0081]of JP 2018-60069A may be mentioned.

As the non-nucleophilic counter ion M⁰⁻, there may be mentioned, forexample, a halide ion such as a chloride ion, a bromide ion, etc., afluoroalkylsulfonate such as triflate, 1,1,1-trifluoroethanesulfonate,nonafluorobutanesulfonate, etc., an arylsulfonate such as tosylate,benzenesulfonate, 4-fluorobenzenesulfonate,1,2,3,4,5-pentafluorobenzenesulfonate, etc., an alkylsulfonate such asmesylate, butanesulfonate, etc., a sulfoneimide such asbis(trifluoromethylsulfonyl)imide, bis(perfluoroethylsulfonyl)imide,bis(perfluorobutylsulfonyl)imide, etc., and a sulfonemethide such astris(trifluoromethylsulfonyl)-methide,tris(perfluoroethylsulfonyl)methide, etc.

As the sulfonium cation of M¹⁺, the materials shown below may bementioned but it is not limited by these. In the following formulae, Meis a methyl group, nBu is an n-butyl group and tBu is a tert-butylgroup.

As the iodonium cation of M¹⁺, those shown below may be mentioned, butthe invention is not limited to these. In the following formulae, tBu isa tert-butyl group and Ph is a phenyl group.

Specific examples of the ammonium cation of M¹⁺ may be mentioned thoseshown below, but the invention is not limited to these.

When the sum of the total composition ratio of the polymer compound ismade 1, compositional ratios (ratios of the repeating units) of therepeating units (p-1), (p-2) and (p-3) are in the range of 0≤(p-1)≤0.3,0≤(p-2)≤0.3, 0≤(p-3)≤0.3 and 0≤(p-1)+(p-2)+(p-2)≤0.3.

By binding an acid generator to the polymer main chain, acid diffusioncan be reduced, and lowering in resolution due to blurring with the aciddiffusion can be prevented. In addition, by the acid generator beinguniformly dispersed, edge roughness (LER and LWR) is improved.

[Repeating Unit (a-1)]

The polymer compound constituting the resist composition of the presentinvention has a repeating unit containing a structure in which apolarity thereof changes by an action of an acid, represented by thefollowing general formula (a-1).

In the above-mentioned formula (a-1), R⁷ is a hydrogen atom or a methylgroup. Y has a structure in which a polarity changes by an action of anacid to become soluble in an aqueous alkali solution.

A difference (ΔC log P) between a C log P of the repeating unit (a-1)and a C log P of the repeating unit (a-1) after changing the polarity byan action of an acid is 3.0 to 4.5.

If the ΔC log P of the formula (a-1) is higher than 4.5, the compoundreleased by an action of an acid is bulky, so that the solubility in analkali developing solution is low, and clogging of the hole pattern andT-top shape in the line pattern are generated. If the ΔC log P is lowerthan 3.0, the height of the resist film is easily decreased, and in theline pattern, pattern collapse is easily caused and depth of focusbecomes narrow.

Specific examples of the monomer which gives the repeating unit (a-1)may be mentioned those shown below, but the invention is not limited tothese.

The difference of a C log P between the formulae (a-1) and (a-1) afterchanging the polarity thereof by an action of an acid is preferably inthe range of 3.3 to 4.2.

The C log P value is confirmed by using a software of ChemDraw Ultra(Registered Trademark) available from Cambridge Soft Corporation. Inorder to reproduce the state at the time of introducing the polymer,calculation was carried out in the state that the polymerizable group ofthe above-mentioned monomer is reduced.

[Repeating Unit (a-2)]

The polymer compound constituting the resist composition of the presentinvention has the repeating unit containing a structure in which apolarity changes by an action of an acid represented by the followinggeneral formula (a-2).

In the formula (a-2), R⁸ is a hydrogen atom or a methyl group. Z⁴ is asingle bond, a methylene group, an ethylene group, a phenylene group, afluorinated phenylene group, —O—Z⁴¹—, —C(═O)—O—Z⁴¹— or —C(═O)—NH—Z⁴¹—,Z⁴¹ is an alkanediyl group having 1 to 12 carbon atoms, and may containa carbonyl group, an ester bond or an ether bond. R⁹ to R¹¹ eachindependently represent a hydrocarbon group which is linear having 1 to10 carbon atoms, or branched or cyclic having 3 to 10 carbon atoms, andamong two of them may be bonded to each other to form a ring.

In addition, the repeating unit represented by the above-mentionedformula (a-2) can be a repeating unit represented by the followingformula (a-2-1).

(In the formula (a-2-1), R⁸ to R¹¹ are as defined above.)

The difference (ΔC log P) between a C log P of the repeating unit (a-2)and a C log P of the repeating unit (a-2) after changing the polaritythereof by an action of an acid is 2.5 to 3.2.

The repeating unit represented by (a-2) is inferior in acid dissociationproperty as compared with that of the repeating unit represented by(a-1) so that it is inferior in dissolution contrast, but it suppressesswelling to the alkali developing solution, prevents pattern collapseand broadens depth of focus. If ΔC log P is out of the range of 2.5 to3.2, it is impossible to take a balance between dissolution-preventingproperty into a developing solution and suppression of swelling afterelimination.

Specific examples of the monomer which gives the repeating unit (a-2)may be mentioned those shown below, but the invention is not limited tothese.

[Repeating Unit (b-1)]

The polymer compound constituting the resist composition of the presentinvention has the following general formula (b-1).

In the formula (b-1), R¹² is a hydrogen atom or a methyl group. Z⁵ is asingle bond, a methylene group, an ethylene group, a phenylene group, afluorinated phenylene group, —O—Z⁵¹—, —C(═O)—O—Z⁵¹— or —C(═O)—NH—Z⁵¹—,Z⁵¹ is an alkanediyl group having 1 to 12 carbon atoms, and may containa carbonyl group, an ester bond or an ether bond. n1 is an integer of 1to 3, n2 is an integer of 0 to 3 and a sum of n1 and n2 is 5 or less.R¹³ is a halogen atom or a hydrocarbon group which is linear having 1 to10 carbon atoms, or branched or cyclic having 3 to 10 carbon atoms,—CH₂— constituting the hydrocarbon group may be replaced by —O—,—C(═O)—O— or —C(═O)—, or a hydrogen atom constituting the hydrocarbongroup may be substituted with a halogen atom or a hetero atom.

Specific examples of the monomer which gives the repeating unit (b-1)may be mentioned those shown below, but the invention is not limited tothese.

The compound containing a phenolic hydroxyl group has a sensitizationeffect, and is excellent in sensitivity and CDU.

[Repeating Unit (c-1)]

The above-mentioned polymer compound may contain the repeating unithaving a lactone structure represented by the following general formula(c-1). (In the following formula (c-1), R¹⁴ is a hydrogen atom or amethyl group. X¹ is a single bond or a hydrocarbon group having 1 to 5carbon atoms and —CH₂-constituting the hydrocarbon group may be replacedby —O—, —C(═O)—O— or —C(═O)—. L is a group having a lactone structure.)

L in the above-mentioned formula (c-1) can be any of the grouprepresented by the following formulae (c-1-1), (c-1-2) and (c-1-3).

In the formula (c-1-1), n3 is an integer of 1 to 4, R¹⁵ is a hydrocarbongroup which is linear having 1 to 10 carbon atoms, or branched or cyclichaving 3 to 10 carbon atoms, —CH₂— constituting the hydrocarbon groupmay be replaced by —O—, —C(═O)—O— or —C(═O)—, or a hydrogen atomconstituting the hydrocarbon group may be substituted with a halogenatom or a hetero atom. n4 represents a linking group having 1 to 5carbon atoms. In the formula (c-1-2), X² is a single bond or ahydrocarbon group having 1 to 5 carbon atoms and —CH₂— constituting thehydrocarbon group may be replaced by —O— or —C(═O)—. n5 is an integer of1 to 4, R¹⁶ is a hydrocarbon group which is linear having 1 to 10 carbonatoms, or branched or cyclic having 3 to 10 carbon atoms, —CH₂—constituting the hydrocarbon group may be replaced by —O—, —C(═O)—O— or—C(═O)—, or a hydrogen atom constituting the hydrocarbon group may besubstituted with a halogen atom or a hetero atom. In the formula(c-1-3), X³ is a single bond or a hydrocarbon group having 1 to 5 carbonatoms and —CH₂-constituting the hydrocarbon group may be replaced by —O—or —C(═O)—. n6 is an integer of 1 to 4, R¹⁷ is a hydrocarbon group whichis linear having 1 to 10 carbon atoms, or branched or cyclic having 3 to10 carbon atoms, —CH₂— constituting the hydrocarbon group may bereplaced by —O—, —C(═O)—O— or —C(═O)—, or a hydrogen atom constitutingthe hydrocarbon group may be substituted with a halogen atom or a heteroatom.

As the structure of the formula (c-1-1), specific examples are mentionedbelow, but the invention is not limited to these. The dotted line is abinding arm.

As the structure of the formula (c-1-2), specific examples are mentionedbelow, but the invention is not limited to these. The dotted line is abinding arm.

As the structure of the formula (c-1-3), specific examples are mentionedbelow, but the invention is not limited to these. The dotted line is abinding arm.

As the repeating unit of (c-1), specific examples are mentioned below,but the invention is not limited to these.

The resist composition of the present invention contains a saltrepresented by the following formula (B).

Ma-CO₂ ⁻M²⁺   (B)

In the formula (B), Ma represents a linear, branched or cyclicmonovalent hydrocarbon group having 1 to 35 carbon atoms which maycontain an oxygen atom(s). Also, one or more hydrogen atoms bonded tothe carbon atom may be substituted with a fluorine atom(s); and M²⁺represents a counter cation having a substituent(s), and is a sulfoniumcation, an iodonium cation or an ammonium cation.

In addition, the salt represented by the above-mentioned general formula(B) can be a salt represented by the following formula (B1).

(In the formula (B1), R¹⁸ to R¹⁹ each independently represent a hydrogenatom, a fluorine atom or a trifluoromethyl group. R²⁰ represents ahydrogen atom, a hydroxyl group, a linear, branched or cyclic,substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, ora substituted or unsubstituted aryl group having 6 to 30 carbon atoms;and M²⁺ is the same as defined above.)

Specific examples of the anionic structure (Ma-CO₂ ⁻) of the formula(B); and the anionic structure of the formula (B1) may be mentionedthose shown below, but the invention is not limited to these.

The sulfonium salt, the iodonium salt and the ammonium salt as thecationic structure M²⁺ of the above-mentioned formula (B) can be shownby the structures similar to the above, but the invention is not limitedto these.

An amount of these salts (B) to be added is more than 0 and 40 parts bymass or less based on 100 parts by mass of the base resin in the resistcomposition, preferably 0.1 to 40 parts by mass, and further preferably0.1 to 20 parts by mass. If it is within the above-mentioned range,there is no fear of causing deterioration of resolution, or the problemof foreign matter after developing the resist or at the time of peeling.

The carboxylic acid has lower acid strength as compared with thesulfonium salt which generates an alkane sulfonic acid in which thea-position of the sulfonic acid has been substituted with a fluorineatom or an alkane sulfonic acid in which the a-position of the sulfonicacid has not been substituted with fluorine atom. Therefore, the cationof the carboxylic acid undergoes, for example, salt exchange with analkane sulfonic acid substituted with a fluorine atom at the a-positionwhich is contained in the polymer compound such as a polymer compoundhaving the repeating unit (p-2), so that it works like a quencher. Acarboxylic acid having lower acid strength has a large quenching abilityand contrast is increased, so that it is excellent in rectangularity ofthe pattern after development or edge roughness.

The resist composition of the present invention may further contain asalt represented by the following formula (B2).

In the formula (B2), R²¹ represents a hydrogen atom or a trifluoromethylgroup. R²² represents a linear, branched or cyclic monovalenthydrocarbon group having 1 to 35 carbon atoms which may contain anoxygen atom(s). Also, one or more hydrogen atoms bonded to the carbonatom may be substituted with a fluorine atom(s). M²⁺ represents acounter cation having a substituent(s), and represents a sulfoniumcation, an iodonium cation or an ammonium cation.

Specific examples of the anionic structure of the formula (B2) may bementioned those shown below, but the invention is not limited to these.

The sulfonium salt, the iodonium salt and the ammonium salt as thespecific examples of the cationic structure M²⁺ of the above-mentionedformula (B2) may be mentioned those having the similar structure asmentioned above, but the invention is not limited to these.

An amount of these salts (B2) to be added is 0 to 40 parts by mass basedon 100 parts by mass of the base resin in the resist composition, andwhen it is formulated, it is preferably 0.1 to 40 parts by mass, andfurther preferably 0.1 to 20 parts by mass. If it is within theabove-mentioned range, there is no fear of causing deterioration ofresolution, or the problem of foreign matter after developing the resistor at the time of peeling.

[Solvent]

The solvent to be used in the present invention may be any organicsolvent as long as it can dissolve the polymer compound, a photoacidgenerator, a quencher, other additives, etc. Such an organic solvent maybe mentioned, for example, as described at the paragraphs [0144] to[0145] of JP 2008-111103A, ketones such as cyclohexanone,methyl-2-n-amylketone, etc., alcohols such as 3-methoxybutanol,3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol,etc., ethers such as propylene glycol monomethyl ether, ethylene glycolmonomethyl ether, propylene glycol monoethyl ether, ethylene glycolmonoethyl ether, propylene glycol dimethyl ether, diethylene glycoldimethyl ether, etc., esters such as propylene glycol monomethyl etheracetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethylpyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propyleneglycol mono-tert-butyl ether acetate, etc., lactones such asγ-butyrolactone, etc., and a mixed solvent thereof. When an acetal-basedacid labile group is used, in order to accelerate deprotection reactionof the acetal, a high boiling point alcohol-based solvent, specifically,diethylene glycol, propylene glycol, glycerin, 1,4-butanediol,1,3-butanediol, etc., may be added.

In the present invention, among these organic solvents,1-ethoxy-2-propanol, propylene glycol monomethyl ether acetate,cyclohexanone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and amixed solvent thereof, which are particularly excellent in solubility ofthe acid generator in the resist components are preferably used.

An amount of the organic solvent to be used is suitably 200 to 12,000parts by mass, particularly 1,000 to 7,000 parts by mass based on 100parts by mass of the base resin.

[Other Components]

The resist composition of the present invention may contain a quencher(nitrogen-containing compound), a surfactant, etc., if necessary.

(Nitrogen-Containing Compound)

In the present invention, a nitrogen-containing compound may be added asa quencher. By adding this material, it is possible to suppress thediffusion rate of the acid generated from the photoacid generator whenit is diffused in the resist film. As such a nitrogen-containingcompound, there may be mentioned a primary, secondary or tertiary aminecompound described at the paragraphs [0146] to [0164] of JP2008-111103A, in particular, an amine compound having a hydroxyl group,an ether bond, an ester bond, a lactone ring, a cyano group and/or asulfonate bond may be mentioned. In addition, as in the compounddescribed in Japanese Patent No. 3,790,649, a compound in which aprimary or secondary amine is protected as a carbamate group may be alsomentioned.

These quenchers can be used a single kind alone or two or more kinds incombination, and a formulation amount thereof is preferably 0.001 to 12parts by mass, particularly 0.01 to 8 parts by mass based on 100 partsby mass of the base resin. By formulating the quencher, in addition tofacilitating adjustment of sensitivity of the resist, a diffusion rateof the acid in the resist film is suppressed to improve resolution,change in sensitivity after exposure is suppressed, the dependence on asubstrate or an environment is reduced, and exposure margin, patternprofile, etc., can be improved. In addition, by adding these quenchers,adhesiveness of the substrate can be also improved.

In addition, a photoacid generator having a nitrogen-containingsubstituent may be used in combination. Such a compound functions as aquencher in a non-exposed area, and functions as a photodegradable basethat loses the ability of quenching by neutralization with an acidgenerated from itself in an exposed area. The use of the photodegradablebase allows for sharper contrast between an exposed area and anon-exposed area. Illustrative example of the photodegradable base mayinclude those in JP 2009-109595A, JP 2012-046501A, etc.

(Surfactant)

To the resist composition of the present invention, a surfactant may beadded. As the surfactant, there may be mentioned a surfactant which isinsoluble or difficultly soluble in water and soluble in an alkalideveloping solution, and/or a surfactant (hydrophobic resin) which isinsoluble or difficultly soluble in water and an alkali developingsolution and, for example, it can be referred to the (S) definitioncomponents described in JP 2010-215608A or JP 2011-16746A.

As the surfactant insoluble or difficultly soluble in water and thealkali developing solution, among the surfactants described in theabove-mentioned publications, FC-4430, SURFLON S-381, SURFYNOL E1004,KH-20, KH-30, and an oxetane ring-opening polymerized productrepresented by the following structural formula (surf-1) are suitable.These may be used singly or two or more kinds in combination.

Here, R, Rf, A, B, C, “m” and “n” are applied only to theabove-mentioned formula (surf-1) regardless of the above-mentioneddescription. R represents a divalent to tetravalent aliphatic grouphaving 2 to 5 carbon atoms, specifically the divalent group may bementioned ethylene, 1,4-butylene, 1,2-propylene,2,2-dimethyl-1,3-propylene and 1,5-pentylene, and the trivalent ortetravalent group may be mentioned the following.

(wherein, the dotted line represents a bonding arm, and each is apartial structure derived from glycerol, trimethylolethane,trimethylolpropane and pentaerythritol, respectively.)

Among these, preferably used is 1,4-butylene or2,2-dimethyl-1,3-propylene. Rf represents a trifluoromethyl group or apentafluoroethyl group, and preferably a trifluoromethyl group. “m” isan integer of 0 to 3, “n” is an integer of 1 to 4, and the sum of “n”and “m” represents the valence number of R and is an integer of 2 to 4.A is 1, B is an integer of 2 to 25, and C is an integer of 0 to 10.Preferably B is an integer of 4 to 20, and C is 0 or 1. In addition, therespective structural units of the above-mentioned structures do notdefine the arrangement thereof, and may be bonded in block or random.For the manufacture of partially fluorinated oxetane ring-openingpolymer-based surfactants, it is described in U.S. Pat. No. 5,650,483,etc., in detail.

The surfactant which is insoluble or difficultly soluble in water andsoluble in an alkali developing solution has a function of reducingpenetration of water and leaching by orientation on the surface of theresist after spin coating when a resist protective film is not used inArF immersion exposure. Therefore, it is useful for suppressing elutionof the water-soluble components from the resist film and reducing damageto the exposure apparatus, and after exposure, it is useful since itbecomes soluble at the time of alkali development after post-exposurebaking (PEB), and it difficultly become a foreign matter which causesdefects. Such a surfactant has characteristics of insoluble ordifficultly soluble in water and soluble in an alkali developingsolution, is a polymer type surfactant and is also called a hydrophobicresin. It can improve solubility of the difficultly soluble surfacelayer even with dry exposure, so that defects can be reduced. Inparticular, a material which improves solubility in an alkali developingsolution is preferable.

Such a polymer type surfactant may be mentioned a polymer compoundhaving repeating units represented by the general formulae (a′-1),(a′-2), (a′-3), b′ and c′ mentioned below, and the like.

In the formulae, R^(e1) are each independently a hydrogen atom, afluorine atom, a methyl group or a trifluoromethyl group. R^(e2) areeach independently a hydrogen atom, or a linear, branched or cyclicalkyl group or fluorinated alkyl group having 1 to 20 carbon atoms, andR^(e2) in the same repeating unit may be bonded to each other to form aring together with the carbon atom to which these are bonded, and inthis case, it is a linear, branched or cyclic alkylene group orfluorinated alkylene group having 2 to 20 carbon atoms in total.

R^(e3) is a hydrogen atom or a fluorine atom, or may be bonded to R^(e4)to form a non-aromatic ring having 3 to 10 carbon atoms together withthe carbon atom to which these are bonded. R^(e4) is a linear, branchedor cyclic alkylene group having 1 to 6 carbon atoms, and one or morehydrogen atoms may be replaced with a fluorine atom(s). R^(e5) is alinear or branched alkyl group having 1 to 10 carbon atoms in which oneor more hydrogen atoms are replaced with a fluorine atom(s), and R^(e4)and R^(e5) are bonded to form a non-aromatic ring together with thecarbon atom to which these are bonded, and in this case, R^(e4), R^(e5)and the carbon atom to which these are bonded form a trivalent organicgroup having 3 to 12 carbon atoms. The above-mentioned trivalent organicgroup may have an ether bond in the non-aromatic ring. R^(e6) is asingle bond, or an alkylene group having 1 to 4 carbon atoms.

R^(e7)s are each independently a single bond, —O— or —CR^(e1)R^(e1)—.R^(e8) is a linear or branched alkylene group having 1 to 4 carbonatoms, and may form a non-aromatic ring having 3 to 6 carbon atoms bybonding to R^(e2) in the same repeating unit together with the carbonatom to which these are bonded. At this time, the hydrogen atom of thenon-aromatic ring may be replaced with a (CF₃)₂C(OH) group.

R^(e9) is a methylene group, a 1,2-ethylene group, a 1,3-propylene groupor a 1,4-butylene group, and may contain an ester bond. R^(e10) is alinear perfluoroalkyl group having 1 to 6 carbon atoms, a3H-perfluoropropyl group, a 4H-perfluorobutyl group, a5H-perfluoropentyl group or a 6H-perfluorohexyl group. When R^(e9) is amethylene group, one or more of the hydrogen atom(s) may be replacedwith R^(e10).

L^(e) are each independently —C(═O)—O—, —O— or —C(═O)—R^(e11)—C(═O)—O—,and R^(e11) is a linear, branched or cyclic alkylene group having 1 to10 carbon atoms.

Also, the copolymerization ratios (molar ratio) of (a′-1), (a′-2),(a′-3), b′ and c′ are 0≤(a′-1)≤1, 0≤(a′-2)≤1, 0≤(a′-3)≤1, 0≤b′≤1 and0≤c′≤1, and 0≤(a′-1)+(a′-2)+(a′-3)+b′+c′≤1.

Here, (a′-1)+(a′-2)+(a′-3)+b′+c′=1 means that, in the polymer compoundcontaining the repeating units (a′-1), (a′-2), (a′-3), b′ and c′, thetotal amount of the repeating units (a′-1), (a′-2), (a′-3), b′ and c′ is100 mol % based on the total amount of the whole repeating units, and(a′-1)+(a′-2)+(a′-3)+b′+c′≤1 means that the total amount of therepeating units (a′-1), (a′-2), (a′-3), b′ and c′ is less than 100 mol %based on the total amount of the whole repeating units and otherrepeating unit(s) than (a′-1), (a′-2), (a′-3), b′ and c′ is contained.

Specific examples of the repeating units are shown below, but theinvention is not limited to these. In the following formulae, R^(e1) hasthe same meaning as defined above.

A weight average molecular weight Mw of the above-mentioned polymer typesurfactant in terms of polystyrene by GPC is preferably 1,000 to 50,000,and more preferably 2,000 to 20,000. If it is within the range, surfacemodifying effect is sufficient and development defect is less likelygenerated.

The above-mentioned surfactant that is insoluble or difficultly solublein water and soluble in an alkali developing solution can be alsoreferred to JP 2008-122932A, JP 2010-134012A, JP 2010-107695A, JP2009-276363A, JP 2009-192784A, JP 2009-191151A, JP 2009-98638A, JP2010-250105A, JP 2011-42789A, and so on.

A formulation amount of the above-mentioned surfactant may be 0 to 20parts by mass based on 100 parts by mass of the base resin, and when itis formulated, the lower limit thereof is preferably 0.001 part by mass,and more preferably 0.01 part by mass. On the other hand, the upperlimit thereof is preferably 15 parts by mass, and more preferably 10parts by mass.

[Patterning Process]

The present invention is further to provide a patterning process whichis a patterning process including forming a resist film on a substrateusing the above-mentioned resist composition, laying a mask over theresist film, exposing the film by irradiating a high energy beam, andthen, developing with an alkali developing solution to form a pattern onthe substrate, wherein the exposure with the high energy beam is carriedout by a KrF excimer laser having a wavelength of 248 nm, an ArF excimerlaser having a wavelength of 193 nm, EUV having a wavelength of 13.5 nm,or electron beam.

For forming a pattern using the resist composition of the presentinvention, it can be carried out by using a conventionally knownlithography technology and, for example, the composition is coated on asubstrate (Si, SiO₂, SiN, SiON, TiN, WSi, BPSG, SOG, an organicantireflection film, etc.) for manufacturing an integrated circuit, oron a substrate (Cr, CrO, CrON, MoSi, etc.) for manufacturing a maskcircuit by a means of spin coating, etc., so that the film thicknessbecomes 0.05 to 2.0 μm, and this is prebaked on a hot plate at 60 to150° C. for 1 to 10 minutes, preferably at 80 to 140° C. for 1 to 5minutes. Then, a mask for forming an objective pattern is laying overthe resist film, and a high energy beam such as KrF excimer laser, ArFexcimer laser or EUV is irradiated so that the exposure amount becomes 1to 200 mJ/cm², preferably 10 to 100 mJ/cm². For exposure, in addition tothe usual exposure method, it is also possible to use an immersionmethod which immerse with a liquid between the mask and the resist filmin some cases. In such a case, it is possible to use a protective filminsoluble in water. Then, post exposure baking (PEB) is carried out on ahot plate at 60 to 150° C. for 1 to 5 minutes, preferably at 80 to 140°C. for 1 to 3 minutes. Further, using a developing solution of anaqueous alkali solution such as 0.1 to 5% by mass, preferably 2 to 3% bymass of tetramethylammonium hydroxide (TMAH) and the like, 0.1 to 3minutes, preferably 0.5 to 2 minutes, development is carried out by aconventional method such as a dipping method, a paddle method, a spraymethod, etc., whereby an objective pattern is formed on the substrate.

As the developing solution for the patterning process of the presentinvention, a developing solution of an aqueous alkali solution such as0.1 to 5% by mass, preferably 2 to 3% by mass of tetramethylammoniumhydroxide (TMAH), etc., can be used as mentioned above.

EXAMPLE

In the following, the present invention will be explained specificallyby referring to Examples and Comparative Examples, but the presentinvention is not limited by these descriptions.

The structures of each repeating unit are shown below.

POLYMER SYNTHETIC EXAMPLES Polymer Synthetic Example 1

Under nitrogen atmosphere, in a flask were charged 5.7 g of Monomer A-1,2.6 g of Monomer B-1, 6.3 g of Monomer C-1, 5.5 g of Monomer D-1, 0.24 gof V-601 (available from FUJI FILM Wako Pure Chemical Corporation), 0.2g of 2-mercaptoethanol and 25 g of methyl ethyl ketone to prepare amonomer-polymerization initiator solution. In a separate flask which wasmade nitrogen atmosphere was charged 23 g of methyl ethyl ketone, andafter heating to 80° C. under stirring, the monomer-polymerizationinitiator solution was added dropwise over 4 hours. After completion ofdropwise addition, stirring was continued while maintaining thetemperature of the polymerization solution at 80° C. for 2 hours, andthen, cooled to room temperature. The obtained polymerization solutionwas added dropwise to 320 g of vigorously stirring methanol, and theprecipitated polymer was separated by filtration. The polymer was washedtwice with 120 g of methanol, and then, dried at 50° C. for 20 hoursunder vacuum to obtain 18 g of white powder state Polymer P-1.

Polymer Synthetic Examples 2 to 44

According to the similar procedure, Polymers P-2 to P-44 weresynthesized with the monomer composition and introducing ratio shown inTable 1.

TABLE 1 Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Polymer (introducing(introducing (introducing (introducing (introducing compound ratio)ratio) ratio) ratio) ratio) P-1  A-1 0.10 B-1 0.20 C-1 0.30 D-1 0.40P-2  A-1 0.15 B-2 0.10 C-2 0.40 D-2 0.35 P-3  A-1 0.10 B-3 0.25 C-1 0.25D-3 0.40 P-4  A-1 0.10 B-4 0.20 C-1 0.30 D-4 0.40 P-5  A-1 0.10 B-5 0.20C-1 0.30 D-5 0.40 P-6  A-1 0.20 B-6 0.25 C-5 0.25 D-6 0.30 P-7  A-1 0.10B-7 0.20 C-1 0.40 D-1 0.30 P-8  A-1 0.10 B-8 0.10 C-2 0.40 D-1 0.40 P-9 A-1 0.20 B-9 0.20 C-1 0.30 D-1 0.30 P-10 A-1 0.15  B-10 0.20 C-1 0.40D-1 0.25 P-11 A-1 0.15 B-1 0.20 C-1 0.30 D-3 0.20 E-1 0.15 P-12 A-2 0.15B-1 0.20 C-5 0.40 D-3 0.25 P-13 A-3 0.15 B-1 0.10 C-6 0.40 D-2 0.20 E-10.15 P-14 A-4 0.10 B-1 0.20 C-9 0.30 D-5 0.40 P-15 A-5 0.10 B-2 0.30 C-50.20 D-5 0.20 E-2 0.20 P-16 A-6 0.15 B-2 0.10 C-6 0.30 D-5 0.45 P-17 A-70.10 B-2 0.20 C-9 0.30 D-5 0.40 P-18 A-8 0.10 B-2 0.10  C-10 0.35 D-10.45 P-19 A-1 0.10 B-2 0.10 C-1 0.30 D-1 0.25 E-3 0.25 P-20 A-2 0.10 B-10.20 C-1 0.30 D-1 0.20 E-4 0.20 P-21 A-2 0.10 B-1 0.20 C-1 0.30 D-2 0.20E-5 0.20 P-22 A-2 0.15 B-1 0.20 C-2 0.20 D-2 0.20 E-6 0.25 P-23 A-3 0.15B-2 0.20 C-1 0.20 D-1 0.20 E-7 0.25 P-24 A-2 0.10 B-2 0.20 C-5 0.30 D-30.25 E-8 0.15 P-25 A-2 0.15 B-2 0.10 C-1 0.35 D-3 0.20 E-9 0.20 P-26 A-20.10 B-3 0.10 C-1 0.30 D-1 0.30 E-7 0.20 P-27 A-4 0.10 B-3 0.10 C-1 0.30D-3 0.25 E-3 0.25 P-28 A-2 0.10 B-3 0.20 C-2 0.20 D-1 0.25 E-4 0.25 P-29A-3 0.10 B-3 0.20 C-5 0.30 D-3 0.20 E-5 0.20 P-30 A-1 0.15  B-11 0.10C-1 0.35 D-3 0.40 P-31 A-1 0.20  B-12 0.10 C-1 0.35 D-5 0.35 P-32 A-20.15  B-13 0.20 C-5 0.30 D-6 0.35 P-33 A-1 0.10  B-14 0.20 C-1 0.20 D-10.30 E-4 0.20 P-34 A-2 0.10  B-15 0.10 C-1 0.35 D-1 0.30 E-7 0.15 P-35A-3 0.10 B-3 0.50 D-5 0.20 E-4 0.20 P-36 A-1 0.15  B-13 0.45 D-1 0.20E-5 0.20 P-37 A-1 0.10 B-3 0.20 C-3 0.30 D-3 0.40 P-38 A-3 0.10 B-4 0.20C-4 0.35 D-4 0.25 E-3 0.10 P-39 A-4 0.10 C-1 0.50 D-1 0.40 P-40 A-4 0.15B-3 0.20 C-1 0.20 E-1 0.45 P-41 A-4 0.10 B-9 0.60 E-1 0.30 P-42 A-4 0.15B-1 0.50 D-2 0.35 P-43 A-4 0.15 B-5 0.20 C-7 0.30 D-3 0.35 P-44 A-1 0.10B-6 0.20 C-8 0.30 D-4 0.40

[Preparation of Resist Composition]

Next, the above-mentioned polymer compounds, various kinds of onium salt1 (generated acid has pKa of −1 or more) and onium salt 2 (generatedacid has pKa of less than −1), and a nitrogen-containing compound weremixed, and an alkali soluble type surfactant: the polymer compound SF-1was added to a part of the resist as a surfactant, and FC-4430 availablefrom Sumitomo 3M Limited was added as a surfactant to all the resistswith 100 ppm and dissolved. After dissolution, the solution was filteredthrough a filter (diameter: 0.2 μm) made of Teflon (RegisteredTrademark) to prepare the resist compositions shown in the followingTables 2-1, 2-2 and 3.

TABLE 2-1 Nitrogen- Polymer Onium Onium containing compound salt 1 salt2 compoud (parts by (parts by (parts by (parts by Solvent Resist mass)mass) mass) mass) (parts by mass) R-1 P-1 100 Salt 6.0 PGMEA 4000 1-1GBL 1000 R-2 P-2 100 Salt 4.0 PGMEA 4000 1-1 GBL 1000 R-3 P-3 100 Salt4.0 Salt 3.3 PGMEA 4000 1-2 2-1 GBL 1000 R-4 P-4 100 Salt 5.0 AQ-3 2.0PGMEA 4000 1-3 GBL 1000 R-5 P-5/ 100/ Salt 4.2 PGMEA 4000 SF-1 7 1-4 GBL1000 R-6 P-6 100 Salt 5.6 PGMEA 4000 1-4 GBL 1000 R-7 P-7 100 Salt 4.0Salt 4.5 PGMEA 4000 1-2 2-1 GBL 1000 R-8 P-8 100 Salt 4.0 PGMEA 4000 1-2GBL 1000 R-9 P-9/ 100 Salt 5.0 Salt 5.7 PGMEA 4000 SF-1 7 1-3 2-1 GBL1000 R-10 P-10 100 Salt 4.0 AQ-3 1.8 PGMEA 4000 1-2 GBL 1000 R-11 P-11100 Salt 6.0 PGMEA 4000 1-1 GBL 1000 R-12 P-12 100 Salt 6.0 PGMEA 40001-1 GBL 1000 R-13 P-13 100 Salt 4.3 PGMEA 4000 1-3 GBL 1000 R-14 P-14100 Salt 6.0 PGMEA 4000 1-1 GBL 1000 R-15 P-15 100 Salt 4.3 PGMEA 40001-3 GBL 1000 R-16 P-16 100 Salt 5.0 PGMEA 4000 1-4 GBL 1000 R-17 P-17100 Salt 5.0 PGMEA 4000 1-1 GBL 1000 R-18 P-18 100 Salt 6.0 PGMEA 40001-1 GBL 1000 R-19 P-19 100 Salt 4.0 PGMEA 4000 1-1 GBL 1000 R-20 P-20100 Salt 5.0 PGMEA 4000 1-1 GBL 1000

TABLE 2-2 Nitrogen- Polymer Onium Onium containing compound salt 1 salt2 compoud (parts by (parts by (parts by (parts by Solvent Resist mass)mass) mass) mass) (parts by mass) R-21 P-21 100 Salt 6.0 PGMEA 4000 1-2GBL 1000 R-22 P-22 100 Salt 4.3 PGMEA 4000 1-4 GBL 1000 R-23 P-23 100Salt 5.0 PGMEA 4000 1-4 GBL 1000 R-24 P-24 100 Salt 5.0 PGMEA 4000 1-2GBL 1000 R-25 P-25 100 Salt 4.3 AQ-3 2.2 PGMEA 4000 1-2 GBL 1000 R-26P-26 100 Salt 5.0 PGMEA 4000 1-1 GBL 1000 R-27 P-27 100 Salt 4.3 PGMEA4000 1-1 GBL 1000 R-28 P-28 100 Salt 4.3 PGMEA 4000 1-1 GBL 1000 R-29P-29 100 Salt 4.3 PGMEA 4000 1-1 GBL 1000

TABLE 3 Nitrogen- Polymer Onium Onium containing compound salt 1 salt 2compound (parts by (parts by (parts by (parts by Solvent Resist mass)mass) mass) mass) (parts by mass) R-30 P-1 100 Salt 4.5 PGMEA 4000 1-5GBL 1000 R-31 P-2/ 100/ Salt 5.0 PGMEA 4000 SF-1 7 1-6 GBL 1000 R-32 P-3100 Salt 5.0 Salt 8.0 PGMEA 4000 1-5 2-1 GBL 1000 R-33 P-4 100 Salt 4.0AQ-1 1.2 PGMEA 4000 2-1 GBL 1000 R-34 P-5 100 Salt 5.0 PGMEA 4000 1-6GBL 1000 R-35 P-7 100 Salt 3.0 AQ-2 2.3 PGMEA 4000 2-1 GBL 1000 R-36 P-3100 AQ-3 2.4 PGMEA 4000 GBL 1000 R-37 P-30/ 100/ Salt 4.3 PGMEA 4000SF-1 7 1-1 GBL 1000 R-38 P-31 100 Salt 6.0 PGMEA 4000 1-1 GBL 1000 R-39P-32 100 Salt 4.8 AQ-4 3.0 PGMEA 4000 1-2 GBL 1000 R-40 P-33 100 Salt4.3 PGMEA 4000 1-3 GBL 1000 R-41 P-34 100 Salt 5.0 PGMEA 4000 1-4 GBL1000 R-42 P-35 100 Salt 4.0 PGMEA 4000 1-2 GBL 1000 R-43 P-36 100 Salt5.0 Salt 7.0 PGMEA 4000 1-3 2-1 GBL 1000 R-44 P-37 100 Salt 4.8 PGMEA4000 1-2 GBL 1000 R-45 P-38 100 Salt 4.3 PGMEA 4000 1-4 GBL 1000 R-46P-39 100 Salt 6.0 AQ-3 2.4 PGMEA 4000 1-2 GBL 1000 R-47 P-40 100 Salt5.0 AQ-4 2.0 PGMEA 4000 1-3 GBL 1000 R-48 P-41 100 Salt 4.3 PGMEA 40001-2 GBL 1000 R-49 P-42 100 Salt 5.0 Salt 6.0 PGMEA 4000 1-4 2-2 GBL 1000R-50 P-43 100 Salt 4.3 PGMEA 4000 1-3 GBL 1000 R-51 P-44 100 Salt 5.0PGMEA 4000 1-2 GBL 1000

Formulae of Onium salt 1 and Onium salt 2, a nitrogen-containingcompound, and a composition of an alkali soluble type surfactant areshown below.

The solvents shown in the above-mentioned Tables are as follows.

PGMEA: Propylene glycol monomethyl ether acetateGBL: γ-butyrolactone

The C log P value was confirmed by using a software of ChemDraw Ultra(Registered Trademark) available from Cambridge Soft Corporation. Inorder to reproduce the state at the time of introducing the polymer, thepolymerizable group of the monomer was calculated in the state ofreduction. The calculation results are shown in Table 4. The ΔC log Pvalue represents the difference between the C log P value beforedeprotection with an acid and the C log P value related to the mainchain after deprotection. In the present invention, in Monomer B-1 toB-15 which correspond to the repeating unit (a-1), polymers using B1 toB10 in which ΔC log P is within the range of 3.0 to 4.5 correspond toExamples, and polymers using B-11 to B-15 which are out of the rangecorrespond to Comparative Examples. Similarly, in Monomers C-1 to C-10corresponding to the repeating unit (a-2), polymers using C-1 to C-2,C-5 to C-6, and C-9 to C-10 in which ΔC log P is within the range of 2.5to 3.2 correspond to Examples, and polymers using C-3 to C-4, C-7 to C-8which are out of the range correspond to Comparative Examples.

TABLE 4 Monomer ClogP ΔClogP B-1 4.10 3.46 B-2 3.94 3.30 B-3 4.34 3.69B-4 4.90 4.25 B-5 4.48 3.84 B-6 4.26 3.62 B-7 3.82 3.18 B-8 4.20 3.55B-9 4.73 4.08 B-10 4.73 4.08 B-11 6.05 5.40 B-12 5.56 4.92 B-13 3.012.37 B-14 2.79 2.14 B-15 2.26 1.61 C-1 4.96 3.12 C-2 4.93 3.09 C-3 5.593.75 C-4 4.18 2.34 C-5 5.34 2.83 C-6 5.31 2.80 C-7 5.96 3.46 C-8 4.552.05 C-9 5.34 2.83 C-10 5.31 2.80

[EUV Exposure Patterning Evaluation (Hole Pattern Evaluation)]

The resist compositions (R-1 to R-29) of the present invention and theresist compositions (R-30 to R-51) for comparison were each coated on asubstrate onto which an organic antireflection film AL-412 availablefrom BRUWER SCIENCE, Inc. having a film thickness of 20 nm had beenformed using CLEAN TRACK Lithius ProZ manufactured by Tokyo ElectronLimited, and baked on a hot plate at 105° C. for 60 seconds to form aresist film with 50 nm. Using an EUV exposure apparatus NXE3300manufactured by ASML Holding, a lattice pattern of 27.5 nm at a size ofthe pitch on the mask of 46 nm was exposed, and after the exposure, aPEB temperature suitable for each resist composition was applied, then,2.38% aqueous tetramethylammonium solution was discharged while rotatingthe wafer to carry out development for 30 seconds in total, the alkalisolution was washed away with water, and the wafer was rotated at a highspeed to remove water.

(Sensitivity Evaluation)

The prepared resist pattern was observed by CD-SEM CG-5000 manufacturedby Hitachi High-Technologies Corporation, and the exposure amount atwhich the hole diameter became 23 nm at a pitch of 46 nm was made theoptimum exposure amount Eop (mJ/cm²).

(Evaluation of Critical Dimension Uniformity (CDU))

The obtained hole pattern was observed by CD-SEM CG-5000 manufactured byHitachi High-Technologies Corporation, and the hole diameter wasmeasured at 32 points with one hole per one sample, 49 holes weremeasured from one sheet of the SEM image, then, the triple value (3σ) ofthe standard deviation (σ) calculated from the results was obtained, 30sheets of SEM images were obtained and the average value of the standarddeviation was made CDU. CDU means that the value is smaller, thecritical dimension uniformity is excellent. CDU is judged to be goodwith about 3.0 or less. DOF indicates depth of focus. It is judged to begood with about 140 nm or more.

TABLE 5 Resist PEB Eop CDU DOF composition (° C.) (mJ/cm²) (nm) (nm)Example 1-1 R-1 90 31 2.5 150 Example 1-2 R-2 80 33 2.6 145 Example 1-3R-3 80 27 2.7 150 Example 1-4 R-4 80 27 2.5 155 Example 1-5 R-5 85 292.4 150 Example 1-6 R-6 90 28 2.4 155 Example 1-7 R-7 95 34 2.5 145Example 1-8 R-8 100 31 2.6 155 Example 1-9 R-9 95 25 2.7 160 Example1-10 R-10 85 30 2.4 160 Example 1-11 R-11 90 32 2.5 155 Example 1-12R-12 90 33 2.4 150 Example 1-13 R-13 85 33 2.4 160 Example 1-14 R-14 8531 2.3 155 Example 1-15 R-15 80 32 2.6 165 Example 1-16 R-16 80 27 2.7145 Example 1-17 R-17 90 30 2.7 150 Example 1-18 R-18 90 34 2.6 155Example 1-19 R-19 85 30 2.5 155 Example 1-20 R-20 80 33 2.6 150 Example1-21 R-21 85 37 2.7 155 Example 1-22 R-22 85 36 2.6 160 Example 1-23R-23 80 35 2.5 165 Example 1-24 R-24 90 35 2.6 160 Example 1-25 R-25 8532 2.8 160 Example 1-26 R-26 80 30 2.6 165 Example 1-27 R-27 85 31 2.5150 Example 1-28 R-28 90 35 2.6 155 Example 1-29 R-29 90 36 2.7 160

TABLE 6 Resist PEB Eop CDU DOF composition (° C.) (mJ/cm²) (nm) (nm)Comparative R-30 95 28 3.2 120 Example 1-1 Comparative R-31 90 30 3.5135 Example 1-2 Comparative R-32 80 25 3.5 135 Example 1-3 ComparativeR-33 80 30 3.8 140 Example 1-4 Comparative R-34 80 30 3.2 100 Example1-5 Comparative R-35 95 26 3.9 95 Example 1-6 Comparative R-36 85 32 3.780 Example 1-7 Comparative R-37 95 28 3.2 165 Example 1-8 ComparativeR-38 90 30 3.5 175 Example 1-9 Comparative R-39 95 31 3.5 120 Example1-10 Comparative R-40 100 36 2.8 105 Example 1-11 Comparative R-41 10537 2.7 100 Example 1-12 Comparative R-42 85 26 2.5 95 Example 1-13Comparative R-43 85 32 2.2 80 Example 1-14 Comparative R-44 95 30 3.5145 Example 1-15 Comparative R-45 100 35 3.6 110 Example 1-16Comparative R-46 100 33 3.8 150 Example 1-17 Comparative R-47 110 33 4.2140 Example 1-18 Comparative R-48 100 30 4.0 160 Example 1-19Comparative R-49 90 32 2.8 75 Example 1-20 Comparative R-50 100 29 3.4140 Example 1-21 Comparative R-51 90 29 3.1 120 Example 1-22

From the results shown in Tables 5 and 6, it was found that the resistcompositions of the present invention (Examples 1-1 to 1-29) had CDU of3.0 or less, and DOF (depth of focus) of 140 nm or more, and in thepositive pattern formation by development of the aqueous alkalisolution, these were excellent in CDU, and sufficiently wide DOF. On theother hand, in Comparative Examples (Comparative Examples 1-1 to 1-22),both of CDU and DOF do not satisfy the above-mentioned numerical range.From the above, it was shown that the resist composition of the presentinvention was useful for the aqueous alkali solution developmentprocess.

Evaluation of Swelling of Resist Composition During Development UsingQCM (Quartz Crystal Microbalance) Method

The resist compositions of the present invention and the resistcompositions of Comparative Examples prepared with the composition shownin Tables 2-1 and 2-2 were each spin coated on a QCM substrate so thatthe thickness became 100 nm, and baked on a hot plate at 105° C. for 60seconds. Thereafter, exposure was carried out at an exposure amount offrom 1 mJ/cm² to 13 mJ/cm² with a step of 1 mJ/cm² by an ArF open flameexposure apparatus, and after the exposure, baking (PEB) was carried outusing a hot plate at a temperature shown in Table 7 for 60 seconds.Thereafter, the resist film on the QCM substrate was observed by using adevelopment analysis apparatus RDA-Qz3 (manufactured by Litho Tech JapanCorporation), that is, variation of the resist film thickness to thedevelopment time in a developing solution of 2.38% by weighttetramethylammonium hydroxide (TMAH) aqueous solution was observed. Fromthe graph showing the development time and variation of the filmthickness in each exposure amount, the exposure amount showing themaximum swelling amount, and the maximum swelling amount ratio (a valuein which the maximum swelling amount is standardized with an initialfilm thickness) are shown in Table 7. As the maximum swelling amountratio is smaller, swelling of the resist film is suppressed.

TABLE 7 Maximum PEB Exposed swelling temperature amount amount Resist (°C.) (mJ/cm2) ratio Example R-1 90 7 133% 2-1 Example R-2 80 6 117% 2-2Example R-12 90 6 132% 2-3 Comparative R-43 85 5 180% Example 2-1Comparative R-46 100 7 110% Example 2-2 Comparative R-49 90 6 201%Example 2-3

From the results of Table 7, it was confirmed that the resistcompositions (Examples 2-1 to 2-3) containing the repeating unit (a-2)of the present invention had smaller maximum swelling amount ratio thanthat of the resist compositions (Comparative Examples 2-1 and 2-3) whichdid not contain the repeating unit (a-2). Comparative Example 2-2contains the repeating unit (a-2) but does not contain the repeatingunit (a-1), so that the maximum swelling amount ratio was confirmed tobe small.

It must be stated here that the present invention is not restricted tothe embodiments shown by Examples. The embodiments shown by Examples aremerely examples so that any embodiments composed of substantially thesame technical concept as disclosed in the claims of the presentinvention and expressing a similar effect are included in the technicalscope of the present invention.

1. A resist composition comprising: a polymer compound having one or tworepeating units selected from repeating units represented by thefollowing general formulae (p-1), (p-2) and (p-3), a repeating unitrepresented by the following formula (a-1) and the formula (a-2)polarities of which are changed by an action of an acid, and a repeatingunit represented by the following formula (b-1); a salt represented bythe following general formula (B); and a solvent, wherein a differencebetween a C log P of the repeating unit (a-1) and a C log P of therepeating unit (a-1) after changing the polarity thereof by an action ofan acid is 3.0 to 4.5, and a difference between a C log P of therepeating unit (a-2) and a C log P of the repeating unit (a-2) afterchanging the polarity thereof by an action of an acid is 2.5 to 3.2:

in the above-mentioned formulae (p-1), (p-2) and (p-3), R¹, R⁴ and R⁶are each independently a hydrogen atom or a methyl group; Z¹ is a singlebond, a phenylene group, —O—Z¹¹—, —C(═O)—O—Z¹¹ or —C(═O)—NH—Z¹¹—; Z¹¹ isan alkanediyl group having 1 to 6 carbon atoms or an alkenediyl grouphaving 2 to 6 carbon atoms, or a phenylene group, each of which maycontain a carbonyl group, an ester bond, an ether bond or a hydroxylgroup; Z² is a single bond, —Z²¹-C(═O)—O—, —Z²¹—O— or —Z²¹—O—C(═O)—, Z²¹is an alkanediyl group having 1 to 12 carbon atoms, and may contain acarbonyl group, an ester bond or an ether bond; R² to R³ are eachindependently a monovalent hydrocarbon group having 1 to 20 carbon atomswhich may contain a hetero atom(s); R⁵ is a hydrogen atom or atrifluoromethyl group; Z³ is a single bond, a methylene group, anethylene group, a phenylene group, a fluorinated phenylene group,—O—Z³¹—, —C(═O)—O—Z³¹— or —C(═O)—NH—Z³¹—, Z³¹ is an alkylene grouphaving 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylenegroup, a phenylene group substituted with a trifluoromethyl group, or alinear, branched or cyclic alkenylene group having 2 to 6 carbon atoms,each of which may contain a carbonyl group, an ester bond, an ether bondor a hydroxyl group; M¹⁺ represents a counter cation having asubstituent(s), and represents a sulfonium cation, an iodonium cation oran ammonium cation; M⁰⁻is a non-nucleophilic counter ion; in theabove-mentioned formula (a-1), R⁷ is a hydrogen atom or a methyl group;Y has a structure that changes its polarity by an action of an acid andbecomes soluble in an aqueous alkali solution; in the above-mentionedformula (a-2), R⁸ is a hydrogen atom or a methyl group; Z⁴ is a singlebond, a methylene group, an ethylene group, a phenylene group, afluorinated phenylene group, —O—Z⁴¹—, —C(═O)—O—Z⁴¹- or —C(═O)—NH—Z⁴¹—,Z⁴¹ is an alkanediyl group having 1 to 12 carbon atoms, and may containa carbonyl group, an ester bond or an ether bond; R⁹ to R¹¹ eachindependently represent a hydrocarbon group which is linear having 1 to10 carbon atoms, or branched or cyclic having 3 to 10 carbon atoms, andtwo of which may be bonded to each other to form a ring; in theabove-mentioned formula (b-1), R¹² is a hydrogen atom or a methyl group;Z⁵ is a single bond, a methylene group, an ethylene group, a phenylenegroup, a fluorinated phenylene group, —O—Z⁵¹—, —C(═O)—O—Z⁵¹— or—C(═O)—NH—Z⁵¹—, Z⁵¹ is an alkanediyl group having 1 to 12 carbon atoms,and may contain a carbonyl group, an ester bond or an ether bond; n1 isan integer of 1 to 3, n2 is an integer of 0 to 3 and a sum of n1 and n2is 5 or less; R¹³ is a halogen atom or a hydrocarbon group which islinear having 1 to 10 carbon atoms, or branched or cyclic having 3 to 10carbon atoms, —CH₂— constituting the hydrocarbon group may be replacedby —O—, —C(═O)—O— or —C(═O)—, or a hydrogen atom constituting thehydrocarbon group may be substituted with a halogen atom or a heteroatom;Ma-CO₂ ⁻M²⁺   (B) in the formula (B), Ma represents a linear, branchedor cyclic monovalent hydrocarbon group having 1 to 35 carbon atoms whichmay contain an oxygen atom(s), and one or more hydrogen atoms bonded tothe carbon atom may be substituted with a fluorine atom(s); and M²⁺represents a counter cation having a substituent(s), and is a sulfoniumcation, an iodonium cation or an ammonium cation.
 2. The resistcomposition according to claim 1, wherein the polymer compound furthercontains a repeating unit having a lactone structure represented by thefollowing general formula (c-1):

in the formula (c-1), R¹⁴ is a hydrogen atom or a methyl group; X¹ is asingle bond or a hydrocarbon group having 1 to 5 carbon atoms and —CH₂—constituting the hydrocarbon group may be replaced by —O—, —C(═O)—O— or—C(═O)—; and L is a group having a lactone structure.
 3. The resistcomposition according to claim 2, wherein L in the formula (c-1) is agroup represented by any of the following formulae (c-1-1), (c-1-2) and(c-1-3):

in the formula (c-1-1), n3 is an integer of 1 to 4; R¹⁵ is a hydrocarbongroup which is linear having 1 to 10 carbon atoms, or branched or cyclichaving 3 to 10 carbon atoms, —CH₂— constituting the hydrocarbon groupmay be replaced by —O—, —C(═O)—O— or —C(═O)—, or a hydrogen atomconstituting the hydrocarbon group may be substituted with a halogenatom or a hetero atom; n4 represents a linking group having 1 to 5carbon atoms; in the formula (c-1-2), X² is a single bond or ahydrocarbon group having 1 to 5 carbon atoms and —CH₂-constituting thehydrocarbon group may be replaced by —O— or —C(═O)—; n5 is an integer of1 to 4; R¹⁶ is a hydrocarbon group which is linear having 1 to 10 carbonatoms, or branched or cyclic having 3 to 10 carbon atoms, —CH₂—constituting the hydrocarbon group may be replaced by —O—, —C(═O)—O— or—C(═O)—, or a hydrogen atom constituting the hydrocarbon group may besubstituted with a halogen atom or a hetero atom; in the formula(c-1-3), X³ is a single bond or a hydrocarbon group having 1 to 5 carbonatoms and —CH₂— constituting the hydrocarbon group may be replaced by—O— or —C(═O)—; n6 is an integer of 1 to 4; and R¹⁷ is a hydrocarbongroup which is linear having 1 to 10 carbon atoms, or branched or cyclichaving 3 to 10 carbon atoms, —CH₂— constituting the hydrocarbon groupmay be replaced by —O—, —C(═O)—O— or —C(═O)—, or a hydrogen atomconstituting the hydrocarbon group may be substituted with a halogenatom or a hetero atom.
 4. The resist composition according to claim 1,wherein a difference between the C log P of the repeating unit (a-1) andthe C log P of the repeating unit (a-1) after changing the polaritythereof by an action of an acid is 3.3 to 4.2.
 5. The resist compositionaccording to claim 2, wherein a difference between the C log P of therepeating unit (a-1) and the C log P of the repeating unit (a-1) afterchanging the polarity thereof by an action of an acid is 3.3 to 4.2. 6.The resist composition according to claim 3, wherein a differencebetween the C log P of the repeating unit (a-1) and the C log P of therepeating unit (a-1) after changing the polarity thereof by an action ofan acid is 3.3 to 4.2.
 7. The resist composition according to claim 1,wherein the salt represented by the general formula (B) is a saltrepresented by the following formula (B1):

in the formula (B1), R¹⁸ to R¹⁹ each independently represent a hydrogenatom, a fluorine atom or a trifluoromethyl group; R²⁰ represents ahydrogen atom, a hydroxyl group, a linear, branched or cyclic,substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, ora substituted or unsubstituted aryl group having 6 to 30 carbon atoms;and M²⁺ represents a counter cation having a substituent(s), a sulfoniumcation, an iodonium cation or an ammonium cation.
 8. The resistcomposition according to claim 2, wherein the salt represented by thegeneral formula (B) is a salt represented by the following formula (B1):

in the formula (B1), R¹⁸ to R¹⁹ each independently represent a hydrogenatom, a fluorine atom or a trifluoromethyl group; R²⁰ represents ahydrogen atom, a hydroxyl group, a linear, branched or cyclic,substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, ora substituted or unsubstituted aryl group having 6 to 30 carbon atoms;and M²⁺ represents a counter cation having a substituent(s), a sulfoniumcation, an iodonium cation or an ammonium cation.
 9. The resistcomposition according to claim 3, wherein the salt represented by thegeneral formula (B) is a salt represented by the following formula (B1):

in the formula (B1), R¹⁸ to R¹⁹ each independently represent a hydrogenatom, a fluorine atom or a trifluoromethyl group; R²⁰ represents ahydrogen atom, a hydroxyl group, a linear, branched or cyclic,substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, ora substituted or unsubstituted aryl group having 6 to 30 carbon atoms;and M²⁺ represents a counter cation having a substituent(s), a sulfoniumcation, an iodonium cation or an ammonium cation.
 10. The resistcomposition according to claim 1, which further comprises a saltrepresented by the following formula (B2):

in the formula (B2), R²¹ represents a hydrogen atom or a trifluoromethylgroup; R²² represents a linear, branched or cyclic monovalenthydrocarbon group having 1 to 35 carbon atoms which may contain anoxygen atom(s), and one or more hydrogen atoms bonded to the carbon atommay be substituted with a fluorine atom(s); and M²⁺ represents a countercation having a substituent(s), a sulfonium cation, an iodonium cationor an ammonium cation.
 11. The resist composition according to claim 2,which further comprises a salt represented by the following formula(B2):

in the formula (B2), R²¹ represents a hydrogen atom or a trifluoromethylgroup; R²² represents a linear, branched or cyclic monovalenthydrocarbon group having 1 to 35 carbon atoms which may contain anoxygen atom(s), and one or more hydrogen atoms bonded to the carbon atommay be substituted with a fluorine atom(s); and M²⁺ represents a countercation having a substituent(s), a sulfonium cation, an iodonium cationor an ammonium cation.
 12. The resist composition according to claim 3,which further comprises a salt represented by the following formula(B2):

in the formula (B2), R²¹ represents a hydrogen atom or a trifluoromethylgroup; R²² represents a linear, branched or cyclic monovalenthydrocarbon group having 1 to 35 carbon atoms which may contain anoxygen atom(s), and one or more hydrogen atoms bonded to the carbon atommay be substituted with a fluorine atom(s); and M²⁺ represents a countercation having a substituent(s), a sulfonium cation, an iodonium cationor an ammonium cation.
 13. The resist composition according to claim 1,wherein the repeating unit represented by the formula (a-2) is arepeating unit represented by the following formula (a-2-1):

in the formula (a-2-1), R⁸ to R¹¹ are as defined above.
 14. The resistcomposition according to claim 2, wherein the repeating unit representedby the formula (a-2) is a repeating unit represented by the followingformula (a-2-1):

in the formula (a-2-1), R⁸ to R¹¹ are as defined above.
 15. The resistcomposition according to claim 3, wherein the repeating unit representedby the formula (a-2) is a repeating unit represented by the followingformula (a-2-1):

in the formula (a-2-1), R⁸ to R¹¹ are as defined above.
 16. A patterningprocess for forming a pattern on a substrate which comprises: forming aresist film on the substrate using the resist composition according toclaim 1, laying a mask over the resist film, exposing the film byirradiating a high energy beam, and then, developing with an alkalideveloping solution to form a pattern on the substrate, wherein theexposure with the high energy beam is carried out by a KrF excimer laserhaving a wavelength of 248 nm, an ArF excimer laser having a wavelengthof 193 nm, EUV having a wavelength of 13.5 nm, or electron beam.
 17. Apatterning process for forming a pattern on a substrate which comprises:forming a resist film on the substrate using the resist compositionaccording to claim 2, laying a mask over the resist film, exposing thefilm by irradiating a high energy beam, and then, developing with analkali developing solution to form a pattern on the substrate, whereinthe exposure with the high energy beam is carried out by a KrF excimerlaser having a wavelength of 248 nm, an ArF excimer laser having awavelength of 193 nm, EUV having a wavelength of 13.5 nm, or electronbeam.
 18. A patterning process for forming a pattern on a substratewhich comprises: forming a resist film on the substrate using the resistcomposition according to claim 3, laying a mask over the resist film,exposing the film by irradiating a high energy beam, and then,developing with an alkali developing solution to form a pattern on thesubstrate, wherein the exposure with the high energy beam is carried outby a KrF excimer laser having a wavelength of 248 nm, an ArF excimerlaser having a wavelength of 193 nm, EUV having a wavelength of 13.5 nm,or electron beam.